This invention relates to teleconference systems and, more particularly, to systems of this character for three or more conferees.
When an important meeting must be convened, and the participants are distant from each other, considerable cost may be incurred for transportation and expenses. Travel time may be an inefficient use of personnel time, may delay action, and fatigue may reduce personnel effectiveness. One way to overcome these problems is to conduct a video teleconference, which allows people in separate locations to meet by means of video cameras and monitors or viewing screens. Each person looks at the others on a TV monitor, and voices are transmitted over audio channels. However, the promise of teleconferencing has not been completely fulfilled in the form of widespread acceptance. This is true, at least in part, because the systems of the prior art themselves introduce unnatural arrangements that interfere with normal conversation.
In the video conference systems shown, for example, in Edson et al, U.S. Pat. No. 3,601,530; Dorros et al, U.S. Pat. No. 3,519,744; and Poirier et al, U.S. Pat. No. 4,054,908 an audio signal developed in response to the conferee presently talking enables the video camera aimed at that conferee. Thus, one conferee at a time is displayed on the video monitor of each of the conferees.
It has also been proposed in United Kingdom Pat. No. 1,173,918; Klein, U.S. Pat. No. 3,725,587; and Klein, U.S. Pat. No. 3,775,563 to display all conferees simultaneously on respective parts of a single television screen. These systems also result in an unnatural arrangement.
Recent experiments at Bell Telephone Laboratories described by E. F. Brown, J. O. Limb and B. Prasada in a paper published in Birmingham, Alabama: Conference Record, 1978 IEEE National Telecommunications Conference, Dec. 1978, at pp. 34.1.1-34.1.4, involved an arrangement of video pictures to give a panoramic view of the "far room", displaying all participants simultaneously, maintaining the same spatial relationship from site to site to give the illusion of a face-to-face meeting. The illusion was further enhanced with the use of stereo for the audio signals which aided the participants in detecting the source of the speech, allowing more than one conversation at a time. While this resulted in an improved conference system, the authors recognized that "distance effect", while reduced, was still present. This was most noticeable when a conferee turned toward and talked to his neighbor. While the authors suggest that this might be minimized by training conferees to converse with the television display when talking to a neighbor, they conclude that the problem may never be completely solved.
It is thus apparent that there are substantial drawbacks when a teleconference system distorts spatial arrangements, for example, by collapsing individuals occupying different positions onto a display screen occupying one position, making the individuals spatially indistinguishable.